Drip irrigation, also called trickle irrigation, is a special type of irrigation system that helps save water and nutrients by slowly releasing water directly to the roots of plants. This can be done from above the ground or below the soil. The purpose is to deliver water exactly where plants need it most and reduce water loss from evaporation. Drip irrigation systems use a network of valves, pipes, tubing, and small devices that control water flow. If the system is designed, installed, maintained, and operated correctly, it can be more efficient than other irrigation methods, such as surface irrigation or sprinkler irrigation.

In 2023, about 3% of farmers worldwide use drip irrigation.

History

Early drip irrigation methods have been used for many years. A book called Fan Shengzhi shu, written in China around the first century BCE, describes using buried, unglazed clay pots filled with water. These pots are sometimes called Ollas and were used to help water plants.

Modern drip irrigation began in Germany in 1860 when scientists tested underground irrigation systems using clay pipes to combine watering and drainage. In the 1920s, this research expanded to include systems with pipes that had small holes.

Later, in Australia, a man named Hannis Thill developed a way to use plastic to hold and spread water in drip irrigation. In Israel, Simcha Blass and his son Yeshayahu created the first plastic emitter for drip irrigation. Instead of using tiny holes that could easily get blocked, their design used larger and longer paths inside the plastic emitter to control water flow using friction. In 1959, Blass built the first experimental system of this type. In 1964, he partnered with Kibbutz Hatzerim to form a company called Netafim. Together, they developed and patented the first practical surface drip irrigation emitter. Modern drip irrigation was invented in Israel during the 1960s. This method improved how efficiently water and fertilizer were used. According to The Times of Israel, this technology was revolutionary and could save 70% of water used to grow rice.

In 1970, Goldberg and Shmueli made an important improvement. In the Arava desert of southern Israel, Shmueli showed that a trickle-irrigation system placed on the soil surface worked very well for growing vegetables, even with salty water. This system helped turn unproductive land into productive areas.

Switching from underground systems to surface systems solved the problem of clogging. Today, drip irrigation is the most efficient way to water crops. There are two types: surface and subsurface. The most common type, surface drip irrigation, was first developed in Israel in 1970. Because of the need to use water more efficiently, many studies have been done to evaluate drip irrigation’s effectiveness for growing various crops.

Netafim created technology to water rice specifically. Rice paddies produce 10% of the world’s methane emissions, which is equal to the emissions from 400 million cars. This technology was first used in Italy, Turkey, and India. A company called N-Drip developed smart drip irrigation for rice paddies. According to a report in The Times of Israel, the N-Drip system increased rice yields by up to 33%, reduced fertilizer use by 50%, cut greenhouse gas emissions like carbon and methane by 50% to 85%, and saved 50% of water.

In the United States, the first drip tape, called Dew Hose, was created in the early 1960s by Richard Chapin and Jaime Leal-Diaz of Chapin Watermatics. A major improvement came in 1987 with the invention of T-Tape by Plastro Irrigation. This tape had the first slit outlet and a laminar flow track, which later evolved into a turbulent flow track that controlled water better. In 2006, Chapin Watermatics was bought by Jain Irrigation and is now part of Jain Irrigation Inc., USA.

Drip tape was first used in California in the late 1960s. By 1988, only 5% of irrigated land in California used this system. However, by 2010, 40% of irrigated land in California used drip irrigation.

A trickle ring is a round device that evenly spreads water around the base of a tree or shrub. It connects to a water supply through a garden hose or tubing adapter and can be part of a larger irrigation system that waters many plants at once. By controlling the flow of water through the trickle ring, soil can be watered at a rate that reduces waste from runoff and evaporation.

Significance

Modern drip irrigation is widely considered the most important invention in agriculture since the 1930s. The impact sprinkler, invented in the 1930s, was the first practical alternative to surface irrigation.

Current developments

To choose the best drip irrigation system for a specific location, it is important to carefully study factors such as the shape of the land, soil type, water availability, the crops being grown, and climate conditions related to farming.

Drip irrigation systems can sometimes use devices called micro-spray heads. These devices spray water over a small area instead of using drip emitters. They are often used for growing trees and vines, which have larger root areas.

Subsurface drip irrigation (SDI) involves placing dripperline or drip tape underground, either permanently or temporarily, near or below the plant roots. This method is becoming more common for watering row crops, especially in areas where water supplies are limited or where water that has been used before and cleaned is used for irrigation.

Global reach and market leaders

In 2012, China and India were growing the most quickly in the use of drip or other micro-irrigation systems. At that time, more than ten million hectares of land worldwide used these technologies. However, this was less than 4 percent of all irrigated land globally. That year, Israel’s Netafim was the top company in the global micro-irrigation market (a position it held in 2018), and India’s Jain Irrigation was the second-largest micro-irrigation company. In 2017, Rivulis purchased Eurodrip and became the world’s second-largest manufacturer of irrigation systems.

Components and operation

Drip irrigation systems use several parts arranged from the water source to the plants. These parts include:

• A pump or equipment that provides pressurized water
• Filters to remove dirt and small particles, sand separators (if needed), dosing pumps, injectors, venturi assemblies for fertilizer, fertilizer tanks, fertigation pumps, and chemigation systems (optional)
• A backwash and filter system controller
• A pressure control valve (pressure regulator)
• Main pipes before the smaller lateral pipes (made of PVC or HDPE, with fittings)
• Valves that can be operated by hand, electronically, or hydraulically, and safety valves
• Smaller polyethylene tubes called "laterals"
• Fittings and tools to connect the parts
• Emitters at the plants (drippers, micro spray heads, inline drippers, or inline drip tubes)

Pumps and valves in drip systems can be controlled manually or automatically using a smart controller.

Most large drip irrigation systems use filters to stop small particles from clogging the narrow paths in the emitters. New technologies now help reduce clogging. Some home systems skip extra filters because tap water is already filtered at the water treatment plant. Manufacturers of drip irrigation equipment usually require filters to be used, and they may not honor warranties if filters are not included. Filters placed just before the final water delivery pipes are strongly recommended to prevent fine particles from settling or entering the system.

Drip and subsurface drip irrigation are often used with recycled wastewater. Rules usually prevent spraying untreated wastewater into the air unless it meets drinking water standards.

In drip systems, traditional fertilizers applied to the soil may not work well because water is delivered directly to the roots. Instead, liquid fertilizer is mixed with irrigation water, a process called fertigation. Fertigation and chemigation (using chemicals like chlorine or sulfuric acid to clean the system) use injectors such as diaphragm pumps, piston pumps, or aspirators. These chemicals can be added continuously during irrigation or at specific times. Recent tests show drip fertigation can save up to 95% of fertilizer compared to other methods.

Properly designed, installed, and managed drip irrigation systems can save water by reducing evaporation and deep drainage compared to flood or overhead sprinkler systems. Water is applied directly to the plant roots, which also helps prevent diseases spread by water touching leaves. In areas with limited water, drip irrigation may not save water but can increase crop production using the same amount of water. In very dry areas or on sandy soil, water should be applied as slowly as possible.

Pulsed irrigation sometimes delivers water in short bursts to reduce runoff or deep percolation. However, pulsed systems are costly and need frequent maintenance. New emitter designs now focus on delivering water at very slow rates (less than 1.0 liter per hour), improving water use efficiency without the cost of pulsed systems.

An emitting pipe is a type of drip irrigation tubing with emitters already installed at set intervals and flow rates for specific crops.

Emitters control water flow by slowing it down, creating the pressure needed to release water as drops. This pressure reduction happens through friction or turbulence inside the emitter.

Advantages and disadvantages

The advantages of drip irrigation are:

• Fertilizers and nutrients are used more efficiently because they are applied directly to the soil and less likely to wash away.
• Water is used well if the system is managed correctly.
• The field does not need to be perfectly flat.
• Fields with unusual shapes can still use this system easily.
• Recycled water that is not safe to drink can be used without problems.
• Soil around plant roots stays at the right moisture level.
• The type of soil has less effect on how often water is needed.
• Soil erosion is reduced.
• Weeds grow less.
• Water spreads evenly, controlled by the flow from each nozzle.
• It requires less labor compared to other irrigation methods.
• Water supply can be adjusted by controlling the valves and drippers.
• Fertilizers can be added with the water with little waste.
• Plant leaves stay dry, which lowers the chance of disease.
• It usually works at lower pressure than other systems, saving energy.

The disadvantages of drip irrigation are:

• It might cost more to set up than other systems. If the system is not set up correctly, the cost of replacing and fixing tubes might be higher than the water savings. It can also require more labor, especially if crops are changed often and tubes need to be replaced each season.
• Sunlight can damage the tubes, making them wear out faster.
• Broken plastic from the tubes might harm the soil and crops. Chemicals from the plastic can be released into the environment when it breaks down.
• If water is not filtered well or equipment is not maintained, the system can get clogged.
• With underground drip systems, the farmer can’t see the water being used, which might lead to using too much or too little water, especially for those with little experience.
• Drip irrigation might not work well if herbicides or fertilizers need to be spread using sprinklers.
• Drip tape needs to be cleaned up after harvest, adding to costs. Users must plan for winding, disposing of, recycling, or reusing the tape.
• If installed wrong, it can waste water, time, and harvest. The system needs careful planning based on land shape, soil, water, crops, and climate.
• In lighter soils, underground drip systems might not wet the soil enough for seeds to grow. Careful planning is needed for how deep the tubes are placed.
• Drip systems are very efficient, so not much water is wasted. However, if not enough water is used, salt can build up in the soil. Drip systems also avoid the problem of salt rising from below the soil in traditional methods.
• PVC pipes can be damaged by rodents, leading to more costs.
• Drip systems can’t protect plants from frost at night like sprinkler systems.

Drip tape

Drip tape is a type of thin-walled dripper line used in drip irrigation. The first drip tape was called "Dew Hose."

Drip tape duct tape is made of polyethylene and is sold flat on reels. The wall thickness usually ranges from 0.1 to 0.6 mm (4 to 25 mils). Thicker-walled tapes are often used for permanent subsurface drip irrigation, while thinner-walled tapes are used for temporary systems in high-value crops.

Water flows out of the tape through emitters or drippers. The typical distance between emitters ranges from 150 to 610 mm (6 to 24 inches). In some products, emitters are made at the same time as the tape and become part of the product. In others, emitters are made separately and added during production.

Some products are not tape but are thin-walled dripper lines. However, both types are often called tapes in common language. Typical tape diameters are 16 mm (5⁄8 in), 22 mm (7⁄8 in), and 35 mm (1 + 3⁄8 in). Larger diameters are more commonly used for permanent installations with longer runs.

Drip tape is a recyclable material that can be turned into usable plastic resins for reuse in the plastics manufacturing industry.

Uses

Drip irrigation is used on farms, commercial greenhouses, and home gardens. It is commonly used in places where water is very scarce and for growing certain plants, such as coconuts, containerized landscape trees, grapes, bananas, ber, eggplant, citrus, strawberries, sugarcane, cotton, maize, and tomatoes.

Drip irrigation kits for home use include a timer, hose, and emitter. Hoses with a diameter of 4 mm (0.16 in) are used for watering flower pots.